The turbulence governed by the Navier–Stokes equation is paramount in many physical processes. However, it has been considered as a challenging problem due to its inherent nonlinearity, non-equilibrium, and complexity. Herein, we review the connections between the velocity derivative skewness S k and the non-equilibrium properties of turbulence. S k , a reasonable candidate for describing the non-equilibrium turbulence, which varies during the non-equilibrium procedure. A lot of experimental or numerical evidences have shown that the perturbation of energy spectrum, which associated with the excitation of large scales, results in an obvious variation of S k , and S k is a negative value in this rapid energy decay process. The variation of positive S k is closely related to the perturbation of transfer spectrum, and this corresponds to the backward energy transfer process. In addition, the ske...

中文翻译：

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速度导数偏度在理解非平衡湍流中的作用

在许多物理过程中，由Navier–Stokes方程控制的湍流是最重要的。然而，由于其固有的非线性，不平衡和复杂性，它被认为是一个具有挑战性的问题。在这里，我们回顾了速度导数偏度S k和湍流的非平衡性质之间的联系。S k，用于描述非平衡湍流的合理候选者，其在非平衡过程中会发生变化。许多实验或数值证据表明，与大尺度激发相关的能谱扰动会导致S k的明显变化，而S k在此快速能量衰减过程中为负值。正S k的变化与转移谱的扰动密切相关，这对应于向后的能量传递过程。另外，...